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1. Remote sensing
Remote sensing is the acquisition of information about an object
or phenomenon without
making physical contact with the object. In modern usage, the
term generally refers to
the use of aerial sensor technologies to detect and classify
objects on Earth (both on the
surface, and in the atmosphere and oceans) by means
ofpropagated
signals (e.g. electromagnetic radiation emitted from aircraft
orsatellites).
2. What is transponder? Relate with uplink and downlink
signal?
Transponder electronics in the satellite that convert uplink
signals to downlink signals.
3. Describe uplink and downlink signal
Uplink frequency: In satellite telecommunications terminology,
uplink means the signal
sent from Earth to the satellite.
Downlink frequency: In satellite telecommunications terminology
downlink means the
signal from the satellite to earth.
4. How would the signal be transmitted when we communicate with
friend at US?
Block Up Converter, is part of the uplink side. Uplink means
from earth to satellite. The
BUC puts the signal on a "carrier" frequency which is an SHF
(super high frequency)
signal. SHF is the frequency range in which satellites operate
on (3GHz to 30GHz).
The LNB, or Low Noise Block converter, is part of the downlink
side (satellite to earth).
Since the antenna receives all the frequencies its satellite is
transmitting, a filter is
needed. The LNB only lets through the block of frequencies
needed.
So here's the signal flow starting from earth.
5. How many geostationary orbit to cover the entire earth?
6. Solar wind
The solar wind is a stream ofcharged particles released from the
upper atmosphere of
the Sun. It mostly consists ofelectrons and protons with
energies usually between 1.5
and 10 keV. The stream of particles varies in temperature and
speed over time. These
particles can escape the Sun's gravity because of their high
kinetic energy and the
high temperature of the corona.
http://en.wikipedia.org/wiki/Atmospherehttp://en.wikipedia.org/wiki/Oceanshttp://en.wikipedia.org/wiki/Wave_propagationhttp://en.wikipedia.org/wiki/Wave_propagationhttp://en.wikipedia.org/wiki/Electromagnetic_radiationhttp://en.wikipedia.org/wiki/Aircrafthttp://en.wikipedia.org/wiki/Satelliteshttp://en.wikipedia.org/wiki/Charged_particlehttp://en.wikipedia.org/wiki/Stellar_atmospherehttp://en.wikipedia.org/wiki/Sunhttp://en.wikipedia.org/wiki/Electronhttp://en.wikipedia.org/wiki/Protonhttp://en.wikipedia.org/wiki/Electronvolthttp://en.wikipedia.org/wiki/Gravityhttp://en.wikipedia.org/wiki/Kinetic_energyhttp://en.wikipedia.org/wiki/Temperaturehttp://en.wikipedia.org/wiki/Coronahttp://en.wikipedia.org/wiki/Coronahttp://en.wikipedia.org/wiki/Temperaturehttp://en.wikipedia.org/wiki/Kinetic_energyhttp://en.wikipedia.org/wiki/Gravityhttp://en.wikipedia.org/wiki/Electronvolthttp://en.wikipedia.org/wiki/Protonhttp://en.wikipedia.org/wiki/Electronhttp://en.wikipedia.org/wiki/Sunhttp://en.wikipedia.org/wiki/Stellar_atmospherehttp://en.wikipedia.org/wiki/Charged_particlehttp://en.wikipedia.org/wiki/Satelliteshttp://en.wikipedia.org/wiki/Aircrafthttp://en.wikipedia.org/wiki/Electromagnetic_radiationhttp://en.wikipedia.org/wiki/Wave_propagationhttp://en.wikipedia.org/wiki/Wave_propagationhttp://en.wikipedia.org/wiki/Oceanshttp://en.wikipedia.org/wiki/Atmosphere
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The solar wind creates the heliosphere, an enormous bubble in
the interstellar
medium that surrounds the Solar System. Other related
phenomena
include geomagnetic storms that can knock out power grids on
Earth,
the aurora (northern and southern lights), and the plasma tails
ofcomets that always
point away from the Sun.
7. Solar sailing
Solar sails (also called light sails or photon sails) are a form
of spacecraft propulsion
using the radiation pressure (also called solar pressure) of a
combination of light and
high speed ejected gasses from a star to push large ultra-thin
mirrors to high speeds.
Light sails could also be driven by energy beams to extend their
range of operations,
which is strictly beam sailing rather than solar sailing.
Solar sail craft offer the possibility of low-cost operations
combined with long operating
lifetimes. Since they have few moving parts and use no
propellant, they can potentially
be used numerous times for delivery of payloads.
Solar sails use a phenomenon that has a proven, measured effect
on spacecraft. Solar
pressure affects all spacecraft, whether in interplanetary space
or in orbit around a
planet or small body. A typical spacecraft going to Mars, for
example, will be displaced
by more than 1,000 km by solar pressure, so the effects must be
accounted for in
trajectory planning, which has been done since the time of the
earliest interplanetary
spacecraft of the 1960s. Solar pressure also affects the
attitude of a craft, a factor that
must be included in spacecraft design.
8. Jet propulsion
( )
http://en.wikipedia.org/wiki/Heliospherehttp://en.wikipedia.org/wiki/Interstellar_mediumhttp://en.wikipedia.org/wiki/Interstellar_mediumhttp://en.wikipedia.org/wiki/Solar_Systemhttp://en.wikipedia.org/wiki/Geomagnetic_stormhttp://en.wikipedia.org/wiki/Aurora_(astronomy)http://en.wikipedia.org/wiki/Plasma_(physics)http://en.wikipedia.org/wiki/Comethttp://en.wikipedia.org/wiki/Comethttp://en.wikipedia.org/wiki/Plasma_(physics)http://en.wikipedia.org/wiki/Aurora_(astronomy)http://en.wikipedia.org/wiki/Geomagnetic_stormhttp://en.wikipedia.org/wiki/Solar_Systemhttp://en.wikipedia.org/wiki/Interstellar_mediumhttp://en.wikipedia.org/wiki/Interstellar_mediumhttp://en.wikipedia.org/wiki/Heliosphere
